I'm considering a batch of 3 blastocyst donor embryos and they are graded 4AB, 4AB, 6CA. I found this website showing a grading system and some cool photos of the embryos:
It looks like they have modified the grading to do A to D rather than A to C. But it looks like they are referencing a pretty standard system. I'm wondering how C.ooper's system works for blasts. Any insight is welcome.